Preparation of cementitious materials from biomass power plant ash and the application of cementitious materials in backfill material

LI Keji; QI Tingye; FENG Guorui; WANG Haochen; WANG Linfei; HE Junjie; CHENG Siyuan; QIU Tian

doi:10.12438/cst.2024-0463

Abstract：The backfill technology using paste-like materials boasts advantages of excellent fluidity and high strength,ensuring long-dis-tance transportation and pressure-bearing capacity,thereby facilitating its rapid development in the coal mining industry.However,its widespread application is hindered by the reliance on costly cement as a binder.To reduce costs,current research explores the utilization of inexpensive biomass power plant ash,processed through hydrothermal synthesis and low-temperature calcination,to fabricate a novel ce-mentitious material as a substitute for cement in backfilling.X-ray diffraction and scanning electron microscopy are employed to analyze the hydrothermally synthesized precursors and the low-temperature calcined clinker,investigating the effects of hydrothermal synthesis and low-temperature calcination on the phase development and microstructure of the novel cementitious material.Orthogonal experiment-al design is adopted to systematically study the impact of various factors and their levels on the properties of the cementitious material,identifying the optimal combination of factors for the hydrothermal synthesis-low temperature calcination process.The feasibility of apply-ing this optimally synthesized novel cementitious material in backfilling is further examined.The results indicate that hydrothermal syn-thesis significantly accelerates the reaction rate,and the precursor obtained via hydrothermal synthesis more effectively transforms into active substances under low-temperature calcination.Optimal performance is achieved when the Ca/Si moral ratio of raw materials is 1.5,the hydrothermal synthesis temperature is 90℃,the duration of hydrothermal synthesis is 3 hours,and the calcination temperature is 850℃.Backfill material prepared with a mass ratio of gangue∶fly ash∶novel cementitious material∶water as 5∶3∶2∶2,using the optimally synthesized cementitious material,meet the requirements for compressive strength and flowability.This study concludes that the novel ce-mentitious material prepared from biomass power plant ash via hydrothermal synthesis and low-temperature calcination can replace ce-ment in backfill materials,reducing the cost of binders in backfill materials.This not only promotes the adoption of paste-like backfill min-ing technology but also facilitates the utilization of biomass power plant fly ash as a solid waste resource.